XY Not?
Another constraint I learned about from a Clover puzzle: imagine each diamond is a white Kropki dot, but instead of the difference between the two digits being one, it’s something else. In fact, if the diamond has digits to the left and right, then the number over in column one is the difference. But if the diamond has digits above and below, then the number up in row one is the difference. That’s X and Y part of XY-Difference Pairs.